> On 10 Feb 2020, at 6:20 AM, Matthew Knepley <knep...@gmail.com> wrote: > > On Sun, Feb 9, 2020 at 3:23 PM Pierre Jolivet <pierre.joli...@enseeiht.fr > <mailto:pierre.joli...@enseeiht.fr>> wrote: > Hello, > I’ve a hard time answering the following DMPlex questions by just looking at > some of the examples and manual. > Considering two DMPlex dm and dma, as in > petsc/src/dm/impls/plex/examples/tests/ex19.c, I’d like to interpolate a > simple P_1 FE function from dm to dma. > The DMCreateInterpolation call gives me: > [0]PETSC ERROR: Invalid argument > [0]PETSC ERROR: Number of fine indices 0 != 4 dual basis vecs > […] > > It looks like your fine grid has no discretization, since 0 is numFIndices > from > > ierr = DMPlexGetClosureIndices(dmf, fsection, globalFSection, cell, > &numFIndices, &findices, NULL);CHKERRQ(ierr); > > [0]PETSC ERROR: #1 DMPlexComputeInterpolatorGeneral() line 2508 in > petsc/src/dm/impls/plex/plexfem.c > [0]PETSC ERROR: #2 DMCreateInterpolation_Plex() line 7688 in > petsc/src/dm/impls/plex/plex.c > [0]PETSC ERROR: #3 DMCreateInterpolation() line 1139 in > petsc/src/dm/interface/dm.c > But the DMs look OK, don’t they, cf. below? > So I have three simple questions: > 1) are all tests at the bottom of ex19.c broken because of PRAgMaTIc or > because of DMPlex currently not supporting some operations? (I’m not using > PRAgMaTIc to do mesh adaptation, so I was hoping to not run into an error) > > I don't think its broken.
Oh, OK. Could you help me figure out what’s the problem then, e.g., with a slight (command line) variation of test #6, please? $ cd src/dm/impls/plex/examples/tests $ git diff ex19.c $ make ex19 $ mpirun ./ex19 -dim 3 -nbrVerEdge 10 -dm_plex_separate_marker 0 -met 0 -hmin 0.1 -hmax 0.3 -init_dm_view -adapt_dm_view -do_L2 -petscspace_degree 1 -petscfe_default_quadrature_order 1 -dm_plex_hash_location [0]PETSC ERROR: Nonconforming object sizes [0]PETSC ERROR: The section point closure size 0 != dual space dimension 4 […] [0]PETSC ERROR: #1 DMProjectLocal_Generic_Plex() line 633 in src/dm/impls/plex/plexproject.c [0]PETSC ERROR: #2 DMProjectFunctionLocal_Plex() line 771 in src/dm/impls/plex/plexproject.c [0]PETSC ERROR: #3 DMProjectFunctionLocal() line 7809 in src/dm/interface/dm.c [0]PETSC ERROR: #4 DMProjectFunction() line 7766 in src/dm/interface/dm.c If I comment the DMProjectFunction() call, I end up with the same error as in my first message in DMCreateInterpolation(). > 2) is DMCreateInterpolation + MatInterpolate the correct way of transferring > one Vec from a DMPlex onto another? > > That is the intent. > > 3) if yes, by looking at the names of the arguments in > DMPlexComputeInterpolatorGeneral, dmc and dmf, could you comment on the > performance of this function for unrelated meshes, e.g., if both DMs are > “fine” and not one coarse and the other fine (albeit non-nested), for simple > P_k spaces. > > In general, it is going to be horrible. Here is what it does: locate the fine > quadrature points in the coarse grid and interpolate to them. This quadrature > can have huge errors if it falls across multiple cells. This is why the > nested version works perfectly, and also why Patrick Farrell and James > Maddison have the Supermesh library, which makes a refinement of the mesh > until the quadrature is accurate everywhere. That way they guarantee that at > least the zeroth moment is preserved. Two subquestions if I may: 1) are there any plans to have this integrated through an external package? 2) if I understand you correctly, you answered about the numerical performance of the function. I can live with high interpolation errors if both meshes are “far" from each other. I was mostly interested in the parallel performance of the function. Thanks, Pierre > Thanks, > > Matt > > Thanks in advance for your help, > Pierre > > $ mpirun -n 1 ./ex19 -msh in.msh -init_dm_view ::ascii_info -adapt_dm_view > ::ascii_info -mat_view ::ascii_info -do_L2 -petscspace_degree 1 > DM Object: DMinit 1 MPI processes > type: plex > DMinit in 3 dimensions: > 0-cells: 1331 > 1-cells: 7930 > 2-cells: 12600 > 3-cells: 6000 > Labels: > depth: 4 strata with value/size (0 (1331), 1 (7930), 2 (12600), 3 (6000)) > Face Sets: 6 strata with value/size (4 (200), 1 (200), 5 (200), 2 (200), 3 > (200), 6 (200)) > Cell Sets: 1 strata with value/size (0 (6000)) > DM Object: DMadapt (adapt_) 1 MPI processes > type: plex > DMadapt in 3 dimensions: > 0-cells: 2905 > 1-cells: 18888 > 2-cells: 31368 > 3-cells: 15384 > Labels: > depth: 4 strata with value/size (0 (2905), 1 (18888), 2 (31368), 3 (15384)) > Face Sets: 6 strata with value/size (1 (200), 4 (200), 6 (200), 2 (200), 5 > (200), 3 (200)) > Cell Sets: 1 strata with value/size (0 (15384)) > > > > > -- > What most experimenters take for granted before they begin their experiments > is infinitely more interesting than any results to which their experiments > lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
